We plan to use retinal transplantation to restore neural cells to extensively damaged adult mammalian retina. To achieve this aim, we will transplant immature dissociated cells, either from the whole neural retina, or neural cell populations enriched by the application of novel methodologies such as layer separation and fluorescence-activated cell sorting. The key hypotheses to be tested are that it will be possible to replace photoreceptor cells and interneurons, and that it may be possible to replace ganglion cells, in rats that have extensive losses of these cells by the action of continuous light exposure or toxic injury. The results will be evaluated by a combination of light and electron microscopy, electrophysiological recordings, and light-induced reflex modification tests. The findings resulting from these studies should provide significant insight as to the eventual feasibility of using neural grafts to repair retinal damage resulting from injury or natural disease.